EPA Accepting Comments on Atrazine Risk Assessment Until October 4

EPA Accepting Comments on Atrazine Risk Assessment Until October 4

Growers and the public can now comment on the EPA's draft ecological risk assessments for the registration review of atrazine, propazine and simazine through October 4. A recent EPA draft report on this class of herbicides could result in a "de facto" ban on them, according to ag officials. Growers are urged to comment.

The Triazine Network insists that if the EPA continues to use the same faulty science relied on in this new preliminary risk assessment, it could effectively eliminate use of the effective herbicide on Iowa corn acres and on other crops across the nation. Iowa farmers use atrazine on at least 56 percent of corn acres to control broadleaf weeds, more than any other crop protection compound, because it works, it's cost-effective and it's safe - for farmers and the environment. Farmers across the U.S. also use it for the same reasons in sorghum, sugarcane, vegetables, tree fruit and turf grass.

EPA Lowers "Level of Concern"

The Triazine Network asserts the federal agency discounted several high-quality studies and instead used studies that the EPA's own 2012 Scientific Advisory Panel (SAP) deemed flawed. The draft report erroneously and improperly estimated atrazine’s levels of concern for birds, fish, mammals and aquatic communities that are not supported by science. According to the latest report, EPA is recommending an aquatic life level of concern (LOC) to be set at 3.4 parts per billion (ppb) on a 60-day average. The EPA's current LOC for atrazine is 10 ppb. However, a diverse universe of scientific evidence points to a safe aquatic life LOC at 25 ppb or greater. One of the most significant studies was from Baylor University in January 2016.

The USDA’s National Agricultural Statistics Service estimated atrazine rate in Iowa was 0.888 pounds per acre per year in 2014. The labeled rate for atrazine in Iowa (in most application situations) is 2 pounds per acre. (Exceptions: 1.6 pounds per acre if less than 30 percent residue; or 2.5 pounds per acre if it’s a post-emergence application following a previous atrazine application.) The average rate per acre used in Iowa is less than labeled rates because atrazine is most commonly used in combination with other products these days, so it provides a broader spectrum of control at a lower rate.

Flexibility in Rate Necessary

However, EPA's latest risk assessment would result in average field application rates as low as 8 ounces per acre (one-quarter pound or one-half pint active ingredient per acre), according to Syngenta. Some watersheds may not be able to use any atrazine. Many farmers and certified crop advisors are concerned that this low of a rate limits the ability to include it in mixes with other products as it would reduce the efficacy of them all, especially on post-emergent broadleaf weeds in corn where more than a half-pound per acre is often necessary to be effective. Some soils and situations call for at least three-quarters to one pound per acre in post-emergence applications, farmers and CCAs say. Yet, there are still situations or locations where one to two pounds are necessary. Options and flexibility on the label are necessary, they say. A lower labeled rate may lead to relying on fewer, more expensive, less effective products, possible weed resistance or the need to increase tillage to control weeds.

EPA’s draft report on the ecological assessment of the herbicide atrazine contains numerous data and methodological errors and needs to be corrected, according to Syngenta scientists. Data presented in the 2012 SAP demonstrated the LOC for atrazine could be more than six times higher and still be protective of aquatic communities, they say. Together with numerous errors in EPA’s modeling, the agency drew scientifically unsound conclusions, based on flawed assessments that need to be corrected.

EPA needs to hear from farmers how the resulting scientifically-flawed lower use rate will impact their conservation efforts, specifically no-till or strip-till production practices, leading to increased soil erosion. EPA needs to understand how their draft risk assessment may jepordize Iowa's ability to implement its Iowa Nutrient Reduction Strategy. Farmers need to ask EPA to provide a scientific justification for disregarding its own Science Advisory Panel recommendations and the results of definitive, independent studies requested by the agency (i.e, the Baylor study, which found that atrazine impacts, if they occur, are temporary on aquatic plant life).

Higher Costs Without Atrazine

The agency also needs to understand that without the availability of atrazine it would cost as much as an additional $28 per acre for a replacement product. A 2012 study by the University of Chicago estimated the loss of atrazine would cost farmers $59 per acre. Given tight margins in today's grain markets, the cost difference could determine whether farmers make any profit of lose money on their crop.

In addition, tell EPA how important sound, accurate, peer reviewed science is to the regulation of all crop protection compounds. The agency needs to be aware of the dangerous precedent when it comes to approving this and other crop protection tools if it abandons the recommendations of its own Science Advisory Panels and the more than 7,000 science-based studies submitted. Not following a robust, science-based regulatory process severely damages EPA's credibility with farmers and the public.

Farmers can learn more about the draft risk assessment at this link, and comment directly to EPA on or before October 4 (the comment period was extended from the original August 5 deadline) by using the "Comment Now" button on the upper-right of the EPA webpage. Farm Bureau members can read previous IFBF comments at this link as background.

Learn more about atrazine at these websites: (sign-up for email updates here),, or, or in this story.

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